A digital camera has an encoder circuit for generating, from YUV signals obtained by imaging, analog video signals or RGB signals for external output, and analog RGB signals for driving a liquid crystal finder. The analog RGB signals for driving the liquid crystal finder are generated by sampling the analog video signals or the RGB signal for external output at a sampling rate corresponding to the number of pixels of a liquid crystal finder.
Unexamined Japanese Patent Applications KOKAI Publication 2001-054134 discloses another type of an encoder circuit which generates, together with analog video signals for external output, and digital RGB signals to be directly supplied to the driving circuit of a TFT liquid crystal display panel constituting the liquid crystal finder.
Image data obtained by imaging in general have a VGA (Video Graphics Array) based pixel configuration of 480 vertical pixels×640 horizontal pixels, which is actually the defacto standard of image processing.
In the case, the video signals to be externally output for Japan's standard television system NTSC are generated from the image data having the VGA pixel number, image data having 704 pixels are generated by multiplying the horizontal pixel number of the VGA by 11/10, by sampling the image data at a frequency of 13.5 MHz derived from the scanning time for one horizontal line. The image data with the horizontal pixel number increased for external output are sampled by a sampling frequency matching with the number of pixels constituting the liquid crystal display panel, and then drives the liquid crystal display with the image data. Ultimately, an image having the VGA aspect ratio of 3:4 is displayed on the liquid crystal display pane.
As described above, the video signals for external output and the signals for liquid crystal display of the finer require each different horizontal pixel numbers, without any correlation between the two pixel numbers. The problem is that the size has to be large of an encoder circuit capable of generating, and outputting, video signals and liquid crystal display signals out of image data provided from the imaging system.
The above-quoted literature fails to disclose anything about the actual number of pixels, etc. relative to the digital RGB signals to be generated.